Conventionally, there has been known a compressor having a configuration in which a compression mechanism and a motor are disposed in a closed casing, and a working fluid (a refrigerant, for example) discharged from the compression mechanism to an internal space of the closed casing is expelled from the compressor through a discharge pipe. In such a compressor, an oil separating member for separating, by utilizing a centrifugal force, an oil from the working fluid being guided to the discharge pipe is used to suppress exit of the oil through the discharge pipe together with the working fluid. For example, Patent Literature 1 discloses a compressor 500 as shown in FIG. 9.
The compressor 500 includes a compression mechanism 503 that is disposed at a lower position in a closed casing 501 and discharges a working fluid to an internal space of the closed casing 501 through an outside pipe 502, and a motor 520 disposed above the compression mechanism 503. A discharge pipe 530 is provided at an upper center of the closed casing 501 so as to penetrate the closed casing 501. An oil separating member 510 is fixed to an upper part of a rotor 521 of the motor 520.
The oil separating member 510 is composed of a flat rotational plate 513, and a conical tube 512 extending upward from an upper face of the rotational plate 513 while contracting radially. That is, the rotational plate 513 and the conical tube 512 form a recess that opens while narrowing upward so as to have an opening smaller than its bottom face. The working fluid flows into the recess through the opening. An inlet that is a lower opening of the discharge pipe 530 is located in the recess. When the oil separating member 510 with the inlet of the discharge pipe 530 being located therein rotates synchronously with the rotor 521, a rotational speed component is given to the working fluid inside the conical tube 512, and thereby oil droplets floating in the working fluid are separated centrifugally. The oil separated from the working fluid lands on an inner wall surface of the conical tube 512 and is guided toward the rotational plate 513 along the inclination of the inner wall surface. Then, the oil is expelled to the outside of the conical tube 512 through an oil release hole 515 provided at a lower end of the conical tube 512.
However, in the conventional configuration shown in Patent Literature 1, since the conical tube 512 is widened downward, the separated oil is guided toward the rotational plate 513 that makes a dead end. Thus, in the case where the oil release hole 515 is too small, the pressure loss in expelling the oil is increased and the oil accumulates on the rotational plate 513 near the inlet of the discharge pipe 530. As a result, the flow of the working fluid picks up the oil again in the working fluid, and the picked-up oil is discharged through the discharge pipe 530. On the other hand, in the case where the oil release hole 515 is too large, the oil separated inside the conical tube 512 cannot close completely the oil release hole 515, and thus the working fluid containing oil droplets shortcuts through the oil release hole 515 and flows into the vicinity of the discharge pipe 530 inside the conical tube 512. As a result, the oil droplets cannot be separated completely from the working fluid being guided to the discharge pipe 530, and thus a large amount of oil is discharged through the discharge pipe 530.
The above-mentioned problems are caused by the shape of the oil separating member in which the recess formed inside thereof has an opening smaller than its bottom face. Therefore, such problems do not arise when the shape of the oil separating member is designed so that the recess formed inside the oil separating member has an opening with a size equal to or larger than the size of its bottom face. For example, Patent Literature 2 discloses a compressor 600 as shown in FIG. 10.
The compressor 600 includes a closed casing 601, a compression mechanism 602, a motor 620 and a discharge pipe 630 like the compressor 500 shown in FIG. 9. An oil separating member 610 in the compressor 600 is in the shape of a saucer. The oil separating member 610 has a bottom wall 617 and a peripheral wall 618. The bottom wall 617 is sandwiched between an end ring 622 and a balance weight 623 so as to be fixed above a rotor 621. The peripheral wall 618 extends upward from a periphery of the bottom wall 617, vertically up to a certain height and expanding therefrom. Furthermore, the discharge pipe 630 has an inlet located in the vicinity of the bottom wall 617 of the saucer-shaped oil separating member 610. The end ring 622 and the bottom wall 617 close an upper end of an oil supply channel 605 penetrating a shaft 603 axially. When the rotation of the rotor 621 rotates the integrally-fixed oil separating member 610, a speed component in the rotational direction is given to the working fluid on an inner side of the peripheral wall 618, and thereby oil droplets floating in the working fluid are separated centrifugally. The oil separated from the working fluid lands on an inner wall surface of the peripheral wall 618 and is guided upward along the inclination of the inner wall surface. Then, the oil is splattered radially outward from an upper end of the peripheral wall 618 by a centrifugal force.